Conventionally, harmful microorganisms such as bacteria, fungus, yeast, and algae are easy to reproduce in various types of industrial products, thereby causing deterioration of productivity or quality, generation of malodor, or the like. Therefore, in order to control the reproduction of these harmful microorganisms, various microorganism control agents which exhibit antimicrobial, antifungal, antiseptic and antialgal effects are widely used.
As an active ingredient of these microorganism control agents, there has been reported that bis-quaternary ammonium salts such as N,N′-hexamethylene bis(4-carbamoyl-1-decylpyridinium bromide) (hereinafter referred to as HMDP-Br in some cases) have a broad antimicrobial spectrum and exhibit excellent control effect (see, for example, the following Patent Document 1).
Further, since the microorganism control agents having HMDP-Br as an active ingredient usually has low solubility of HMDP-Br in water, it is prepared as a solution dissolved with an organic solvent capable of dissolving HMDP-Br at high concentration.    Patent Document 1: Japanese Unexamined Patent Publication No. 2004-143061